At the moment, in regionprops perimeter is for 2D images only, but with the marching cubes functions we have everything to compute the surface areas of connected components.

Also, for perimeters in 2D we could compute them in another way than what is done at the moment, using the contour returned by find_contours. It would give a more accurate estimation of the perimeter I think.

What do you think? It's something I could work on if there is enough interest.

Definition of done: Add 3D properties for surface area and volume, according to the following nomenclature:

I.e., area gets customized for 3D region, volume gets added as new property.